Android 滑动效果进阶篇（六）—— 倒影效果

http://blog.csdn.net/sunboy_2050/article/details/7483169

上篇介绍了使用Animation实现3D动画旋转翻页效果，现在介绍图片倒影实现，先看效果图



本示例主要通过自定义Gallery和ImageAdapter（继承自BaseAdapter）实现

1、倒影绘制

ImageAdapter继承自BaseAdapter，详细实现可见 Android 滑动效果入门篇（二）—— Gallery 这里重点介绍倒影原理及实现

倒影原理：

倒影效果是主要由原图+间距+倒影三部分组成，高度大约为原图的3/2（原图为1、倒影为1/2）

原图，就是我们看到了最开始的图片

间距，是原图与倒影之间的间隙，如：reflectionGap = 4;

倒影，是原图下半部分1/2高度，通过矩阵变换matrix.preScale(1, -1); 获取倒立图片，然后再加上线性遮罩和阴影实现

倒影实现：

[java] view
plaincopyprint?

/** 反射倒影 */

public boolean createReflectedImages() {

final int reflectionGap = 4;

int index = 0;

for (Map<String, Object> map : list) {

Integer id = (Integer) map.get("image");

Bitmap originalImage = BitmapFactory.decodeResource(mContext.getResources(), id); // 获取原始图片

int width = originalImage.getWidth();

int height = originalImage.getHeight();

Matrix matrix = new Matrix();

matrix.preScale(1, -1); // 图片矩阵变换（从低部向顶部的倒影）

Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false); // 截取原图下半部分

Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height / 2), Config.ARGB_8888); // 创建倒影图片（高度为原图3/2）

Canvas canvas = new Canvas(bitmapWithReflection); // 绘制倒影图（原图 + 间距 + 倒影）

canvas.drawBitmap(originalImage, 0, 0, null); // 绘制原图

Paint paint = new Paint();

canvas.drawRect(0, height, width, height + reflectionGap, paint); // 绘制原图与倒影的间距

canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null); // 绘制倒影图

paint = new Paint();

LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0, bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);

paint.setShader(shader); // 线性渐变效果

paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN)); // 倒影遮罩效果

canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint); // 绘制倒影的阴影效果

ImageView imageView = new ImageView(mContext);

imageView.setImageBitmap(bitmapWithReflection); // 设置倒影图片

imageView.setLayoutParams(new myGallery.LayoutParams(180, 240));

imageView.setScaleType(ScaleType.MATRIX);

mImages[index++] = imageView;

}

return true;

}

2、myGallery

自定义Gallery来实现倒影图片的浏览与选择

[java] view
plaincopyprint?

public class myGallery extends Gallery {

private Camera mCamera = new Camera();

private int mMaxRotationAngle = 60; // 最大旋转角度 60

private int mMaxZoom = -120;

private int mCoveflowCenter;

public myGallery(Context context) {

super(context);

this.setStaticTransformationsEnabled(true);

}

public myGallery(Context context, AttributeSet attrs) {

super(context, attrs);

this.setStaticTransformationsEnabled(true);

}

public myGallery(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

this.setStaticTransformationsEnabled(true);

}

public int getMaxRotationAngle() {

return mMaxRotationAngle;

}

public void setMaxRotationAngle(int maxRotationAngle) {

mMaxRotationAngle = maxRotationAngle;

}

public int getMaxZoom() {

return mMaxZoom;

}

public void setMaxZoom(int maxZoom) {

mMaxZoom = maxZoom;

}

/** 获取Gallery的中心x */

private int getCenterOfCoverflow() {

return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft();

}

/** 获取View的中心x */

private static int getCenterOfView(View view) {

return view.getLeft() + view.getWidth() / 2;

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

mCoveflowCenter = getCenterOfCoverflow();

super.onSizeChanged(w, h, oldw, oldh);

}

@Override

protected boolean getChildStaticTransformation(View child, Transformation trans) {

final int childCenter = getCenterOfView(child);

final int childWidth = child.getWidth();

int rotationAngle = 0;

trans.clear();

trans.setTransformationType(Transformation.TYPE_BOTH); // alpha 和 matrix 都变换

if (childCenter == mCoveflowCenter) { // 正中间的childView

transformImageBitmap((ImageView) child, trans, 0);

} else { // 两侧的childView

rotationAngle = (int) ( ( (float) (mCoveflowCenter - childCenter) / childWidth ) * mMaxRotationAngle );

if (Math.abs(rotationAngle) > mMaxRotationAngle) {

rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle : mMaxRotationAngle;

}

transformImageBitmap((ImageView) child, trans, rotationAngle);

}

return true;

}

private void transformImageBitmap(ImageView child, Transformation trans, int rotationAngle) {

mCamera.save();

final Matrix imageMatrix = trans.getMatrix();

final int imageHeight = child.getLayoutParams().height;

final int imageWidth = child.getLayoutParams().width;

final int rotation = Math.abs(rotationAngle);

// 在Z轴上正向移动camera的视角，实际效果为放大图片; 如果在Y轴上移动，则图片上下移动; X轴上对应图片左右移动。

mCamera.translate(0.0f, 0.0f, 100.0f);

// As the angle of the view gets less, zoom in

if (rotation < mMaxRotationAngle) {

float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));

mCamera.translate(0.0f, 0.0f, zoomAmount);

}

mCamera.rotateY(rotationAngle); // rotationAngle 为正，沿y轴向内旋转； 为负，沿y轴向外旋转

mCamera.getMatrix(imageMatrix);

imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));

imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));

mCamera.restore();

}

}

3、Activity

Activity中，主要实现自定义Gallery的图片填充ImageAdapter、myGallery选择事件监听、点击事件监听

[java] view
plaincopyprint?

private void initRes(){

tvTitle = (TextView) findViewById(R.id.tvTitle);

gallery = (myGallery) findViewById(R.id.mygallery); // 获取自定义的myGallery控件

adapter = new ImageAdapter(this);

adapter.createReflectedImages(); // 创建倒影效果

gallery.setAdapter(adapter);

gallery.setOnItemSelectedListener(new OnItemSelectedListener() { // 设置选择事件监听

@Override

public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

tvTitle.setText(adapter.titles[position]);

}

@Override

public void onNothingSelected(AdapterView<?> parent) {

}

});

gallery.setOnItemClickListener(new OnItemClickListener() { // 设置点击事件监听

@Override

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

Toast.makeText(Main.this, "img " + (position+1) + " selected", Toast.LENGTH_SHORT).show();

}

});

}

main.xml布局文件中，通过实现自定义的myGallery，来显示图片集合

[html] view
plaincopyprint?

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical" >

<TextView

android:id="@+id/tvTitle"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:textSize="16sp" />

<com.homer.reflect.myGallery

android:id="@+id/mygallery"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_below="@id/tvTitle"

android:layout_marginTop="10dip" />

</RelativeLayout>

源码下载

参考推荐：

Android实现图片的倒影效果

Android中图片倒影、圆角效果重绘